Mission Control Guide Mission Control Guide
Lesson: Math Detectives
Objectives
Identify clue words for addition/subtraction.
Solve mixed word problems within 1,000.
Solve two-step operation problems.
Pacing
60 Minutes | Grades 3-4
1. The Hook (5 mins)
"Class, today we aren't just students—we are Math Detectives. Every word problem is a mystery waiting to be solved. To do it, we need to find the evidence (the numbers) and the clues (the operation words)."
2. Operation Recon (15 mins)
Review clue words. **Addition:** Total, Altogether, Sum, In All. **Subtraction:** Difference, How many more, Left, Remained.
Focus: "How many more" sounds like adding but is a subtraction comparison.
3. Field Work (30 mins)
Students work on Case File Worksheet. Monitor for multi-step errors where students stop after one operation.
Common Misconceptions
Keyword Dependency
Seeing "more" and adding automatically. Encourage tape diagrams to visualize the comparison.
One-and-Done
Stopping after the first step in a multi-step problem. Model checking the final question.
Answer Key
Classified Information
Case File Worksheet
1
Stadium tickets: 342 Fri + 258 Sat
600 tickets
2
Pilot mission: 850 total - 475 flown
375 miles
3
Library: 125 + 215 - 85 out
125 + 215 = 340; 340 - 85 = 255 books
4
Train: 450 - 120 off + 75 on
450 - 120 = 330; 330 + 75 = 405 passengers
Case Closed Exit Ticket
$500 budget - $135 gadget - $45 fuel.
500 - 135 = 365
365 - 45 = $320 left
Operation Recon Slides Operation Recon
Detective Training Manual: Mixed Operations
The Briefing
Addition Clues
• Combined
• Altogether
• Sum
• Total
• Increased by
Subtraction Clues
• Difference
• Remaining / Left
• How many more?
• Decreased by
• Fewer than
Multi-Step Recon
1
Identify the Hidden Question
What do we need to calculate first before we can answer the main question?
2
Solve & Substitute
Take your first answer and use it in the final operation.
Live Case Study
Classified
"Detective, we have a problem. The bakery started with 450 donuts. In the morning, they sold 125 donuts. In the afternoon, they baked 75 more. How many donuts are in the bakery now?"
Step 1: Subtraction
450 - 125 = 325
Step 2: Addition
325 + 75 = 400
Ready for Field Work?
Grab your Case File Worksheet. Remember: underline the clues, find the evidence, and watch out for multi-step traps!
Worksheet
20 Mins
Case File Worksheet Case File Worksheet
DEPARTMENT OF MATHEMATICAL INVESTIGATIONS
Lead Detective
Mission Date
Instructions: Read each case carefully. Underline clue words and numbers. Show your work clearly in the Evidence Box.
1
The local stadium sold 342 tickets on Friday and 258 tickets on Saturday. How many tickets were sold in total?
Evidence Box
2
A pilot is flying a 850-mile mission. They have already flown 475 miles. How many miles remain in the mission?
Evidence Box
Multi-Step Case
3
The school library has 125 mystery books and 215 science books. During lunch, 85 books were checked out. How many books are still in the library?
Step 1 (First Operation)
Step 2 (Final Answer)
Multi-Step Case
4
A train started with 450 passengers. At the first stop, 120 passengers got off. At the second stop, 75 passengers got on. How many passengers are on the train now?
Step 1 (First Operation)
Step 2 (Final Answer)
Case Closed Ticket Confidential
Case Closed
Final Clearance Exit Ticket
Agent Name:
"Detective, here is your final challenge: Agent X started with $500 for their mission. They spent $135 on a new gadget and $45 on fuel. How much money does Agent X have left?"
Show Your Work (Evidence):
Final Answer:
Mission Success Confidence:
Expert
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